: Public concern has been raised about possible adverse effects of powerline (60-Hertz) electromagnetic fields (EMFs) on the nervous system. Our research will address this question by identifying and examining the mechanisms by which EMFs effect neural cells at the cellular, subcellular and molecular levels and thus alter key cellular functions. Isolated adrenal chromaffin cells will be used as an in vitro model of sympathetic nervous system function for these studies. In preliminary experiments, exposing chromaffin to magnetic flux densities in the 0.8 - 1.4 millitesla (mT) range caused both a rise in intracellular calcium and a stimulation catecholamine release. These EMF-induced effects will be further investigated in the proposed research. Studies will employ fluorescence calcium imaging techniques and 45Ca2+ uptake measurements to elucidate the mechanisms that underlie EMF-induced increases in intracellular calcium. These same two methodologies, in conjunction with assay of catecholamines by high performance liquid chromatography (HPLC), will be used to establish the long-term effects of EMFs on catecholamine release as well as catecholamine biosynthesis rates will be determined. These studies will employ HPLC and radioisotopic labeling methods to assess intracellular levels of catecholamines and their precursors, in situ and in vitro assays to assess alterations in activity of catecholamine biosynthetic enzymes and molecular biology techniques to study changes in the level of expression of tyrosine hydroxylase, the enzyme that catalyzes the rate-limiting step in the catecholamine biosynthetic pathway. The long-term significance of the proposed research is the important information that will be obtained regarding cellular effects of EMFs on neural cells. Such information will be essential for evaluating potential health risks associated with EMF exposure, as well as aiding our understanding of potential therapeutic strategies employing EMFs.